Apparatus for burning lime and cement



June 6, 1933. E. J. wEcHTER APPARATUS FOR BURNING LIME AND CEMENT FiledMay 1l Patented June s, 1933 UNITED STATESv PATENT ort-'ICE EUGENE J'.WECHTEB, 0F SPEED, INDIANA, ASSIGNOB T0 LOUIBV'JILE mi' GOI- PAN'Y, OFLOUISVILLE, KENTUCKY, A CORPORATION 0F KENTUCKY APPARATUS FOB BURNINGLIME AND CEHENT Application led lay 11, 1027. Serial In. 190,475.

A leading purpose of this invention is to provide an apparatus forburning lime and cement, in krock form of those sizes which cannotsuccessfully be burned in vertical kilns, namely, of those sizes fromthree to four inches down to dust. The sizes named constitute abouttwenty-five per cent of lime rock or natural cement rock and ordinarilyare thrown away or used for other purposes. Hence, an apparatus whichwill successfully and economically calcine or burn these small sizes ofrock will introduce important economies since it will enable the plantto convert all of its raw material into calcined material, by usingvertical kilns for the larger rock and an apparatus of the constructionconstituting the subject of the instant application for its smallerrocks.

In` an application for patent filed by me of even date herewith, SerialNo. 190,476, I have shown, described and claimed a method by whichthesesmall sizes of rock may be successfully burned in a kiln of the rotarytype. In the complete method set forth in the said application, the rawmaterial is gradually preheated, the gradual preheating thereof beingimportant since it avoids all danger of explosions of the materialinseparably connected with the introduction of the cold and wet materialinto a flowing current of heated gas or products of combustion having ahigh temperature. In the method referred to, the cold and wet materialis introduced into a current of heated gas at a comparatively lowtemperature and travels in avdirection counter to that of the flow ofthel gases and is gradually raised in temperature thereby until it hasbeen substantially deprived of its moisture and has reached atemperature favorable for subsequent treatment.I

This preheated material is then dis-v charged into a rotary kiln andflows from the feeding end of the kiln to the discharging end thereof inheat transferring relationship with a heated agent which is introducedinto the kiln at that end thereof at which the preheated materialenters, and flows through the kiln in the same direction as thematerial. The material has a lesser depth at that end of the kiln atwhich it 1s introduced than it has further along in the kiln.

In other Words, the method referred to contemplates the formation withinthe kiln of what has been referred to as a burning r combustion zone,which is near the feedlng end of the kiln and at the place where theheating agent has the. highest temperature and the material the lesserdepth, and a roasting zone, Within which the material has the greaterdepth and the heating agent substantially constant temperature. From theroasting zone, the material is discharged in its hot roasted conditionand a current of atmospheric air is passed'through this mass of hot,roasted material but out of contact therewith and is forced underpressure with the fuel into the feeding end of the kiln. This air coolsthe roasted material and is heated thereby and supports combustionwithin the kiln. The products of combustion, after the have passedthrough the kiln, are with awn from the discharge end of the latter andare conducted to the discharge end of the preheater and serve as theagent which preheats the material. The flow inthe preheater is counterto that of the material traversing the preheater and it is drawn olfthrough a stack adjacent the end at which the raw material enters thepreheater.

The instant invention relates primarily to an apparatus by which theforegoing method or process may be carried into effect in the mostpractical way.

Incidental objects of the invention are to provide an apparatus by whichlime and natural cement in rock form and in sizes which are notordinarily successfully burned in vertical kilns may be uniformly burnedin a rotary kihi without danger of overburning; will be economical inthe use of fuel; and will otherwise utilize the waste heat ofcombustion.

With these objects in view as well as others as may become apparent fromthe following disclosure, reference will now be had to the accompanyingdrawing in which drical body having its Ait more convenient or desirableto arrange Fig. 1 is a longitudinal sectional view of the apparatus,some parts being in elevation.

Fig. 2 is a longitudinal sectional view depicting a modification of thepreheating structure.

Referring to the drawing, designates a ho per which receives the rawmaterial and om which the material is fed b means of the feeding tube 11into the feedy end of the reheater 12.

' e preheater 12 is referably a cylineed end projecting into a chamber13 and its discharge end projecting into a chamber 14.

Pre erably, and as illustrated in Fig. 1, the preheater is rotatable andhas its ends loosely mounted in the chambers 13 and 14 and is inclineddownward from the feed end to the discharge end in order that thematerial will travel from the feed to the discharge end by means ofthe-combined action of gravity and the rotation of the preheater.

In order to effect rotation of the preheater it is provided with a ringgear 15 which is rotated by means of a pinlon 16 which is driven bymeans of a suitable sprocket drive 17.

yIn order to prevent the escape of gases A where the ends of thepreheater loosely project into the chambers 13 and 14, rings 18 and 19closely engage the feed and discharge ends of the preheaterrespectivelyiand are provided with anges 20 which are secured .to thechambers. The rings 18 and 19 each confine a suitable washer or'gasket21 which tightly surrounds the preheater.

The chamber 13 is provided with a stack or draft 22 projecting from thetop thereof. When the conditions are such as to make the preheaterhorizontally, the structure shown in Fig. 2 may be used in which acylindrical body 12 has its ends rigidly mounted in the chambers 13a and14a and is provided with a. suitable endless conveyor 23 by means ofwhich the material is carried from the feed to the discharge end of thepreheater.

Located below the structure above described is na rotary kiln 24 whichcomprises a cylindrical member inclined downward from the feed end tothe discharge end, the feed end of the kiln preferably being adja- `centto the discharge end of the preheater.

The kiln 24 is provided with rings 25 adjacent to its ends which ringsengage between langes 26 of suitable rollers 27. The kiln is rotated bymeans of a ring gear 28 secured to the kiln and engaging a pinion 29driven by a suitable sprocket drive 30.

The kiln 24 has its feed end loosely projecting into a cap member 31 andits discharge end loosely projecting into a chamber 32.

A gas tight connection 33 similar to the connection above referred tofor the ends of the preheater Yis provided where the discharge end ofthe kiln enters the chamber 32. n The kiln is preferabl reduced indiameter adjacent to its feedY end, as designated at 34 in order'thatthe hot gases will come more intimately into contact with the material.

Extending transversely through the bottom of the chamber 32 is aplurality of tubes 35 which are in communication'with a chamber 36.

. The numeral 37 desi nates a suitable fan and communicating wlth thefan and the chamber 36 is a tube 38.

In communication with the fan and extending therefrom into the feed endof the kiln is a tube 39.

In communication with the tube 39 is a suitable conveyor 40 by means ofwhich a suitable fuel is introduced into the kiln.

The feed end of the kiln is in communication with the bottom of thechamber 14 through a conduit 41 by which the material is fed from thedischarge end of the preheater to the feed end of the kiln.

In order to prevent gases passing from the kiln into the chamber 14 asuitable Hap valve 42 is provided in the conduit 41.

The discharge end of the kiln 24 is preferably provided with a ring orperforated cap 43 in order that a greater mass of material will remainin the kiln and thus be subjected to a longer period of heat Atreatment.

In communication with and extending from the chamber 32 to the chamber14 is a suitably insulated conduit 44. The product is discharged throughthe bottom of the stack 32 and conveyed to any desired place by means ofa suitable conveyor 45.

It will be noticed that the depth of the material at that end of thekiln at which the material in its preheated condition enters the kiln isless than its depth within the remainder of the kiln. This is importantsince it insures a rapid rise in temperature of the preheated materialand the substantial retention of the material at its lattervtemperature:due to the fact that the material almost immediately after it enters thekiln and while it is of its lesser depth in the kiln comes into testpart of the flame and then progresses throughout the remainder of thekiln with the nroducts of combustion whose temperature has become lessand then remains substantially constant while the depth of the materialhas become greater. The portion of the kiln in which the temperature ofthe material is raised to the calcining point has been herein referredto as the burning or combustion zone and the remainder of the kiln hasbeen referred to as the roasting contact with the hotzone to distinguishthem from each other: although in a broad sense, of course, all parts ofthe kiln may, in fact,"constitute a urning zone and all arts a roastingzone.

It is, of course, di cult and unnecessary to set forth accurately-herein the exact boundaries of the hottest parts of the flame, or anyprecise point at which the burning zone, so called, ends and theroasting zone, so called, commences: but the zone which has been hereinreferred to as the burning zone may be arbitrarily aumed to be thatportion 1n the length ofthe kiln which 1s traversed b the raw materialduring the period in w ich it is being raised to the calcining*temperature, and is of the lesser depth. The zone which has beenreferred to as the roasting zone for the (purposes ofV this explanationmma be assume to be that portion of the kiln t rough which the materialpasses after it has been raised to a calcining temperature and is of thegreater depth and during which it is substantially maintained at saidtemperature.

It may be here mentioned that in my practice, and with a kiln of about100-125 feet in length, I have found that the best results have beensecured when the fuel at its point of ignition (which is about ten feetfrom its inlet to the kiln) has a temperature of about 2000 F. andl aflame temperature of about 2500 F. a few feet further along in the kiln,while the temperature of the gases of combustion at the outlet from thekiln is about 1400 F.4 and at theinlet to the preheater about 1250 F.,radually reducing within the preheater to a ut 300 F. where it iirstcomes in contact with the raw material and then enters the stock 22.` Atthese the preheater at a temperature of about 500 F.800 F. and will bequickly raised in the kiln to an optimum temperature to lose carbondioxide as 1250 F.1400 F., or ,thereabouts5 in the case of naturalcement rock or 1500 F.-1600 F., or thereabouts, in the case of lime.These temperatures may vary, as is evident. i

I have also found it to bebeneficial to maintain the material at a depthvarying from about one `foot in what has been referred to as theburningzone to about two feet in what has been referred to as the roastingzone.

In the use of the apparatus described, the rock is introduced into thehopper 10 and by the action of gravity is fed through the 'tube 11` intothe feed end of the preheater.

The material slowly travels from the feed.

` end to the discharge end of the .preheater by means of the rotation ofthe preheaterv and the action of gravity or by mea-ns of the conveyor23. Since vthe material first comes 55 in contact with the coolestportion of the temperatures, the raw material will leave' end ofthapreheater through the tube 41' into the f end of the kiln 24.

Fuel is introduced at the feed end of the kiln by the conveyor 40 andthe `fan 37..

draws air through the tubes 35 thus heatin the air and thence throughthe tube 38 an fan's the heated air with the fuel into the feedend ofthe v The material is thus subjected to the most intense heat in therestricted portion or burnin zone 34 of the kiln, in which it is of theesser de th. The materia travels from the burning zone and enters theportion of the kilnlo the greatest diameter, in which it isV of theeater depth and has its speed correspondmgly reduced, and in thisportion of the kiln is mainly subjectedto a roasting action.

The hot burned material primes` out of the discharge end of the kilninto the bottom of the stack 32 with the tubes 35 imbedded therein andthus heating the air drawn through the tubes by means of the fan 37.

The waste heat of combustion in the kiln is, by mealis of the stack erdraft 22, drawn thro h thil conduit 44 into the discharge end o thepreheater and therein to the feed end ofthe preheater over the rawmaterial which is slowly descending in the preheater thus drying andpreheating the material before it enters the kiln.

The apparatus, due to its construction, also is ca able of burning highgrade limestonevan natural cement rock of` all small sizes down to dustin a much shorter period of time than that required in the burning oflime or cement rock of the lar r sizes in the usual vertical type ofkiln, t e usual time required for burnin lime and cement in the verticalkiln being rom 24 to 72 hours whereas only from three to six hours, orthereabouts, aregrequired in the apparatus forming this invention.

In short, this apparatus provides a means for burning lime and cement inwhich the entire ma of raw material can be burned moreuniformly, moreeconomically and in a shorter period of time than heretofore, andinwhich the product compares favorably withvthat burned in the verticaltype of kiln.

In conclusion it may be here stated that although reference has nothereinbefore been fmade to the fact, yet in the use of this apparatus inthe treatment of the special materials h erein named, a portion of thecarbonic acid-approximatel fromiive to ten per cent thereofis expe edfrom the raw material in itspassage through the preheat- 1. An apparatusfor the burning of limestone or natural cement, in rock form, comrisinga rotary kiln, a preheating chamber iiaving openings throu h wh1ch therocks to be treated are initial y fed into and d1scharged from saidchamber, respectively, means separate from each other through which thepreheated rocks dlscharged from the preheating chamber and a combustlblefuel, respectively, are independently del 1v ered into the same end ofthe rotary k1ln, said kiln having means at its o pos1te end throughwhich the calcined .roc s `are dlscharged, and means, includlng aconduit extendin between the discharge end of the rotary kiln and thedischarge openlng of the reheating chamber, through wh1ch the prodhctsof combustion which have treated the rocks in the kiln in a parallelflow with said rocks are conducted to the discharging end of thepreheating chamber for the 1nitial treatment of the rocks in the latterby a flow through said chamber counter to that of the rocks.

2. An apparatus for the treatment of lime- |stone or natural cement, inrock form, com' prising a rotary kiln, a preheating chamber, meansthrough which the rocks are fed into one end of the preheating chamber,means through which the preheated rocks are d1scharged from the otherend of the preheating chamber and into the kiln, means forming part ofthe kiln and operatlve to form the rocks therein into a mass whose depthat the receiving end of the kiln is less than its depth throughout thesucceeding part of the kiln, means by which a combustible fuel isintroduced under pressure into that end of the kiln in which said massis of the lesser depth, and means by which the gases which have passedthrough the kiln are introduced into the material discharging end of thepreheater and caused to flow through the latter in a direction counterto that of the raw material.

3. In an apparatus for burning limestone or natural cement, in rockform, a rotary kiln, and means for introducing a combustible fuel underpressure into the material receiving end of said kiln, means formingpart of the kiln and by which the material is formed into a mass whosedepth at the hottest part of the flame formed from said fuel is lessthan that throughout the succeeding portion of the kiln, for thepurposes specified.

4. In an apparatus for burning limestone or natural cement, in rockform, a rotar kiln, having an opening at one en througilI which the rawmaterlal is introduced and also having a member partially closing itsother end and causing an increase in the depth the dischar e end of thekiln and means through wh1ch .a combustible fuel is introduced into thematerial receiving end of the kiln independently of the material andcauses the hottest part of the llame formed therefrom to be in thatportion of the kiln which contains the lesser depth of the raw material.

5. An apparatus for burning lime and cement, in rock form, comprising arotary kiln having its material receiving end of restricted internaldiameter and also having at its material discharging end amember whichpartially closes the latter end and provides a shoulder adjacent thedischarge opening to cause an increase in the depth of material towardsaid discharge end, and means through which a combustible fuel isintroducedunder pressure into the kiln at the material receiving end ofthe latter to cause the hottest part ofthe flame to be in that part ofthe length of the kiln which is of restricted diameter vand contains thelesser depth of material.

6. An apparatus for burning limestone or natural cement, in rock form,comprising a rotary kiln having means through which rocks to be calcinedare delivered into one of its ends and means through which the comprisincalcined rocks are discharged from its other end, a chamber incommunlcation with the discharge end of the kiln to receive the hotcalcined rocks therefrom, said chamber having means through which saidrocks are discharged from it, an atmospheric air pipe embedded in thehot calcined material in said chamber, a fuel supply means, means havingAcommunication at one of its ends with said atmospheric air pipe and atits other end with the fuel supply means and through which air preheatedin said pipe is delivered to the fuel, and means through which themixture of fuel and preheated air is discharged under pressure into theend of the kiln at which the rocks to be treated are delivered andseparately from said rocks.

7. An apparatus for burning limestone or natural cement, in rock form,comprising a preheating chamber through which the raw material is movedprogressively from one end to the other thereof, a draft stack at thematerial receiving end of the' preheating chamber, a chamber at theopposite end of the preheating chamber to receive the materialdischarged from the preheating chamber, a conduit leading from thechamber at the discharge end of the preheating chamber, a rotary kiln tothe material receiving of the material towardl end of which said conduitis connected, a

^ chamber at the discharge end of the kiln to receive the treatedmaterial therefrom, means independent of said conduit and through whicha combustible fuel is discharged into the material receiving end of thekiln and a conduit to lead the gases of combustion at its opposite end,and also including a fan operatively related to said conduit to draw thepreheated airv through said atmospheric pipe and to force it, with thefuel, 1nto the material-receiving end of the kiln. In testimony whereofI aiiix my signature. EUGENE J. WECHTER. v

from the latter chamber tothe chamber at a conduit leading from thechamber at the dischar e end of the preheating chamber, a rotary liln tothe material receiving end of which said conduit is connected, meansseparate from said conduit throughwhich a fuel material is su plied tosald receiving end of the kiln, a c amber at the dischargeA end of thekiln to receive the treated material therefrom, an atmospheric air pipeextending through the mass of hot treated material in the latterchamber, means by which air is caused to flow through said pipe and ismixed-with the fuel material to support combustion of the latter and acon- 4 duit to lead the gases of combustion from -the chamber at thematerial discharging end of the kiln to the chamber at the materialdischarging end of the preheating chamber.

9. An apparatus for burning lime or cement, in rock form, comprising arotary kiln, separate means through which the material to be treated anda fuel respectively are independently discharged into the same endplortlon of said'kiln, and means through whic a current of air is causedto ow throu h, but out of contact with the burned material at theopposite end of the kiln and is forced under pressure, with the fuel,

directly into the first mentioned end of the kiln 1d. An apparatus for iburning lime or# cementin rock form, comprising a rota kiln, havingmeans at one end throug which the raw material is delivered into it andmeans at its op osite end from which said material is di discharging amixture of preheated atmospheric air and a fuel into thematerial-receiving end of the kiln separately from the material to betreated, the latter means including a pi o en at one endA to theatmosphere an em ded in the hot ca lcined material discharged .from thekiln and a conduit. having communication with the `discharge end of saidpipe at one end and with the material-receiving end of l'the' kilnarged, and means for

